SEO

I just saw this while compiling -current:

===> libexec/identd
cc -O2 -pipe -Wall -c /usr/src/libexec/identd/identd.c
cc -O2 -pipe -Wall -c /usr/src/libexec/identd/openbsd.c
/usr/src/libexec/identd/openbsd.c: In function `k_getuid6':
/usr/src/libexec/identd/openbsd.c:89: warning: comparison is always
false due to limited range of data type
/usr/src/libexec/identd/openbsd.c:92: warning: comparison is always
false due to limited range of data type

The lines in question are:

89: if (faddr->sin6_len > sizeof(tir.faddr))
return -1;
memcpy(fin, faddr, faddr->sin6_len);
92: if (laddr->sin6_len > sizeof(tir.laddr))
return -1;
memcpy(lin, laddr, laddr->sin6_len);

Both faddr and laddr are of type struct sockaddr_in6.
(defined in netinet6/in6.h), and the sin6_len member
is a u_int8_t:

struct sockaddr_in6 {
u_int8_t sin6_len; /* length of this
struct(sa_family_t)*/

tir.faddr and tir.laddr are of type struct sockaddr_storage,
defined in sys/socket.h:

struct sockaddr_storage {
u_int8_t ss_len; /* total length */
sa_family_t ss_family; /* address family */
unsigned char __ss_pad1[6]; /* align to quad */
u_int64_t __ss_pad2; /* force alignment for stupid
compilers */
unsigned char __ss_pad3[240]; /* pad to a total of 256 bytes */
};

Since sockaddr_storage is padded to 256 bytes there is indeed no way
that [fl]addr->sin6_len can be larger than sizeof(struct sockaddr_storage).

So I'm wondering whether the checks in lines 89 and 92 of
libexec/identd/openbsd.c are really bogus or if there is a reason for
them, like explicitely guarding the code against future type size changes?
If so, is there a way to get rid of the warning but still retain the
safety net?

This has been in the tree for 7 years now so I doubt no one
has seen this warning before...

Just curious, thanks,
--
stefan
http://stsp.name PGP Key: 0xF59D25F0

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